Add validation to allowed directories on config load #5461

Job	Run time
Lint	4m 32s
Build Unsigned Snapshot	2m 9s
Unit Tests	2m 24s
Performance Tests	7m 17s
Unit tests with race condition detection	2m 45s
Integration Tests - Official Plus Images (debian, bookworm, r32, debian, /nginx-plus/agent)	8m 9s
Integration Tests - Official OSS Images (bookworm, stable, debian)	7m 59s
Integration Tests - Official Plus Images (debian, bookworm, r31, debian, /nginx-plus/agent)	7m 48s
Integration Tests - Official Plus Images (alpine, 3.20, r32, alpine, /nginx-plus/agent)	7m 32s
Integration Tests - Official OSS Images (alpine, stable, alpine)	7m 21s
Integration Tests - Official Plus Images (alpine, 3.19, r31, alpine, /nginx-plus/agent)	7m 45s
Integration Tests (redhatenterprise, 9)	9m 10s
Integration Tests - Official OSS Images (alpine, mainline, alpine)	7m 20s
Load Tests	4m 46s
Integration Tests - Official OSS Images (bookworm, mainline, debian)	7m 55s
Integration Tests (alpine, 3.22)	7m 19s
Integration Tests (ubuntu, 24.04)	9m 30s
	1h 51m 41s

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